What does Jerry accomplish by swimming through the tunnel in the story "Through the Tunnel"?

Jerry completes a rite of passage by successfully swimming through the underwater tunnel.

When the English boy Jerry, who is on holiday with his mother, first leaves her and goes to the bay, he swims out to where rocks are "like discolored monsters under the surface," and he finds himself out in the real sea. Then, he swims back to a cape with "a loose scatter of rocks" where some older boys, native to the coast, run.

To be with them, of them, was a craving that filled his whole body.

When one of them smiles and waves, Jerry swims in and out of the rocks with them. But, when they realize that he is a foreigner and does not understand them, they ignore him. Still, they part for him to dive with them. Shortly after this, the largest boy dives and does not soon reappear. Worried that something has happened to him, Jerry cries out in warning. However, after some time, this boy resurfaces and the others dive into the water in the same manner. Jerry can see nothing when he plunges under the water, but when he surfaces, the others are all on the first rock in order to repeat their feats. "They looked down gravely, frowning." Jerry is embarrassed and acts silly, splashing the water and yelling in English, "Look at me! Look!" But, as he does this, water fills his mouth and he sinks, then resurfaces; in the meantime, the older boys have all dived down into the water caves of rock. When they resurface, they return to the shore without looking back at him.

So, in his embarrassment Jerry returns to his mother's beach and tells her that he wants some swimming goggles right away. He pesters his mother until she goes with him to a shop. After she makes the purchase, Jerry grabs the goggles and runs to the bay where he can now search for the opening in the rocks through which the older boys have swum. Having found the hole in the great rock, Jerry returns to the hotel, dreaming of it at night. The next day he rushes to the bay and he practices holding his breath so that he can be able to swim through this tunnel.

After four days his mother tells him that they must soon return home. So Jerry decides that he will complete his passage through the underwater tunnel on the day before they depart. He goes to the bay with his goggles and although his lungs are now in condition, Jerry's head pulses. Nevertheless, he perseveres and he successfully swims through the tunnel. "Victory filled him" as he feels more mature. When he tears off his goggles a clout of blood washes into the sea, but he just splashes his face clear of anything. Then, he sees the local boys, but now "he did not want them." He just wants to go home. After he rests, Jerry swims to the shore and returns to his mother with the knowledge that he can do what the older boys can; he merely tells him mother that he can hold his breath for two or three minutes. He has made his rite of passage into adolescence: "It was no longer of the least importance to go to the bay."